KCSAN: data-race in probe_sched_wakeup / tracing_stop_cmdline_record

Status: moderation: reported on 2026/08/24 07:48
Subsystems: trace
Labels: race:benign
[Documentation on labels]
Reported-by: syzbot+6081b58df5a5a2bf38af@syzkaller.appspotmail.com
First crash: 18h56m, last: 18h56m
✨ AI Jobs (1)
ID Workflow Result Correct Bug Created Started Finished Revision
0dab1502 assessment-kcsan Benign: ✅ KCSAN: data-race in probe_sched_wakeup / tracing_stop_cmdline_record 2026/08/24 07:47 2026/08/24 07:48 2026/08/24 08:08 1e72964b

Sample crash report:
==================================================================
BUG: KCSAN: data-race in probe_sched_wakeup / tracing_stop_cmdline_record

read-write to 0xffffffff895ee1e0 of 4 bytes by task 5659 on cpu 0:
 tracing_stop_sched_switch kernel/trace/trace_sched_switch.c:120 [inline]
 tracing_stop_cmdline_record+0x28/0xc0 kernel/trace/trace_sched_switch.c:140
 __ftrace_event_enable_disable+0x323/0x4b0 kernel/trace/trace_events.c:848
 ftrace_event_enable_disable kernel/trace/trace_events.c:934 [inline]
 ftrace_clear_events kernel/trace/trace_events.c:1057 [inline]
 ftrace_event_set_open+0xe6/0x200 kernel/trace/trace_events.c:2892
 do_dentry_open+0x49f/0xa60 fs/open.c:996
 vfs_open+0x37/0x1e0 fs/open.c:1101
 do_open fs/namei.c:4837 [inline]
 path_openat+0xc01/0x10d0 fs/namei.c:5000
 do_file_open+0x16c/0x290 fs/namei.c:5029
 do_sys_openat2+0xa0/0x130 fs/open.c:1417
 do_sys_open fs/open.c:1423 [inline]
 __do_sys_openat fs/open.c:1439 [inline]
 __se_sys_openat fs/open.c:1434 [inline]
 __x64_sys_openat+0xf2/0x120 fs/open.c:1434
 x64_sys_call+0x1f72/0x2550 arch/x86/include/generated/asm/syscalls_64.h:258
 do_syscall_x64 arch/x86/entry/syscall_64.c:61 [inline]
 do_syscall_64+0x112/0x360 arch/x86/entry/syscall_64.c:84
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

read to 0xffffffff895ee1e0 of 4 bytes by task 5658 on cpu 1:
 probe_sched_wakeup+0x41/0xa0 kernel/trace/trace_sched_switch.c:45
 __traceiter_sched_wakeup+0x26/0x40 include/trace/events/sched.h:178
 __do_trace_sched_wakeup include/trace/events/sched.h:178 [inline]
 trace_sched_wakeup include/trace/events/sched.h:178 [inline]
 ttwu_do_wakeup kernel/sched/core.c:3740 [inline]
 ttwu_do_activate+0x201/0x230 kernel/sched/core.c:3837
 ttwu_queue kernel/sched/core.c:4087 [inline]
 try_to_wake_up+0x43f/0x6a0 kernel/sched/core.c:4425
 autoremove_wake_function+0x10/0x50 kernel/sched/wait.c:404
 __wake_up_common kernel/sched/wait.c:109 [inline]
 __wake_up_common_lock kernel/sched/wait.c:126 [inline]
 __wake_up_sync_key+0x52/0x80 kernel/sched/wait.c:193
 __unix_dgram_recvmsg+0x3a4/0x860 net/unix/af_unix.c:2615
 unix_dgram_recvmsg+0x7e/0x90 net/unix/af_unix.c:2689
 sock_recvmsg_nosec+0xc2/0xf0 net/socket.c:1151
 ____sys_recvmsg+0x26f/0x280 net/socket.c:2931
 ___sys_recvmsg+0x11f/0x3a0 net/socket.c:2975
 do_recvmmsg+0x1e5/0x560 net/socket.c:3070
 __sys_recvmmsg net/socket.c:3144 [inline]
 __do_sys_recvmmsg net/socket.c:3167 [inline]
 __se_sys_recvmmsg net/socket.c:3160 [inline]
 __x64_sys_recvmmsg+0xe5/0x170 net/socket.c:3160
 x64_sys_call+0x77f/0x2550 arch/x86/include/generated/asm/syscalls_64.h:300
 do_syscall_x64 arch/x86/entry/syscall_64.c:61 [inline]
 do_syscall_64+0x112/0x360 arch/x86/entry/syscall_64.c:84
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

value changed: 0x0000095a -> 0x00000959

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 UID: 0 PID: 5658 Comm: syz.6.587 Not tainted syzkaller #0 PREEMPT(lazy) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/24/2026
==================================================================

Crashes (1):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2026/08/24 07:47 upstream 388b607d107c 1e72964b .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in probe_sched_wakeup / tracing_stop_cmdline_record
* Struck through repros no longer work on HEAD.